The objectives of this proposal are to provide statistical and data management support to the Pediatrics Division of the Southwest Oncology Group (SWOG). The applicants will play an active role in protocol design (which goes well beyond sample size determination, data monitoring, and data quality assurance. An active and continuous dialogue will be sought with SWOG clinical investigators, a genuinely multi-modal group. The statistics office staff will prepare reports for the semi-annual SWOG meeting and take an active role in manuscript preparation in collaboration with clinical researchers. The statisticians will conduct research in statistical methods for cooperative study groups. Unique features of the methodology include (1) interactive data entry, editing, and verifying using microcomputers; (2) close data monitoring (telephone relapse reports) using sequential control charts; (3) quality control of subjective investigator or coordinator judgement (patient evaluability, toxicity, or response) through an in house Pediatric Oncologist; (4) statistical support for SWOG ancillary studies and (5) registration of all SWOG Pediatric Tumor patients.